Title: Satori, The Girl Who Knew Too Much
Circle: IOSYS
Vocal: あゆ
Original: Satori Maiden ~ 3rd eye [Satori Komeiji - SA stage 4 boss theme]
Comment: A remix by IOSYS, anything else you want to know?
Title: ハート物色
Circle: O-Life Japan
Vocal: no
Original: Hartmann's Youkai Girl [Koishi Komeiji - SA EX stage boss theme]
Comment: I have been looking for a remix of Koishi's theme like this for a while. This is the best I have found. Clear and delicate, whimsy and cheerful; exactly what I expect to hear from Koishi. The remix title means "search in heart" I believe.
Title: Hell for Flandle
Circle: Bubble Records
Vocal: no
Original: U.N. Owen was Her? [Flandre Scarlet - EoSD EX stage boss theme]
Comment: A bit scary, middle of a night maybe the best time for it.
Title: Fight on Darkness -Complete mix-
Circle: CTBR
Vocal: no
Original: Complete Darkness [Mima - SoEW final stage boss theme]
Comment: Old song, but still very good.
Edit:
Title: コイイロノユメ
Circle: SOUND HOLIC
Vocal: めらみぽっぷ
Original: Love-Colored Master Spark [Marisa Kirisame - IN stage 4 boss theme]
Visual: 森井ケンシロウ
Comment: Too bad a lot of info. are Japanese only, I want to know more about it, especially the lyrics (in English).